During the course of orthodontic treatment, small appliances and attachments, commonly known as “braces”, are affixed to the teeth of the patient. While there are various types of such appliances and attachments available for use in orthodontic treatment, for the purposes of the current invention and its application, our discussion is limited to an attachment method or “brace” known in the trade as a band. A band is a one-piece ring, made of a thin metal alloy, to which various orthodontic attachments can be welded or soldered. An orthodontic band is designed to fit around the circumference of a tooth in much the same manner as a ring would fit around the circumference of a finger. Just as rings are manufactured in a wide range of sizes to fit various fingers, bands are manufactured in a wide range of sizes to fit various sized teeth. Once the proper band size is chosen for a particular tooth, it is then secured on the tooth by lining the inner surface of the band with a luting material, placing the band in the proper position around the circumference of the tooth, and allowing the luting agent to “dry” or harden. More succinctly, the band is simply glued, or cemented, to the tooth.
In order to fit and place a band on a particular tooth, it is first necessary to have access to the entire circumference of the tooth. Should a portion of the tooth remain obstructed or covered by the surrounding soft tissue, known as gingiva, it is first necessary to retract the obstructing tissue away from the tooth sufficiently to allow circumferential access. After the band is fitted and cemented, the tissue is allowed to relax to its original position, covering a portion of the band as well as the original portion of the tooth. Thus after cementation, some part of the band may remain in the narrow space (the “gingival sulcus”) between the tooth and the gingiva.
Due to their anatomy, molars and premolars, collectively known as the posterior teeth, often pose a particularly difficult banding problem. The chewing surface (the “occlusal surface”) of a posterior tooth contains a deep fissure or groove known as the “central groove” that traverses the length of this surface. When gingival tissue is found obstructing a portion of a posterior tooth near the central groove, a relatively wide segment of tissue may be found obstructing the tooth in the areas adjacent to the central groove, and an additional, much narrower segment of tissue often extends well into the central groove. Prior to fitting or cementing a band, this tissue must first be retracted to allow access to the full circumference of the tooth.
Currently existing dental tools and instruments, though not necessarily designed for tissue retraction, are often of appropriate shape and size to retract gingival tissues for the purposes of orthodontic banding. If tissue only needs to be retracted from the central groove, any instrument sufficiently narrow to fit into the groove could be used to retract this tissue. If there is no tissue in the central groove, there are several instruments adaptable to retracting wider segments of tissue away from a tooth surface. But when both the central groove and any other area are obstructed, a dilemma arises. Those instruments narrow enough to retract tissue from the central groove are insufficiently wide to adequately retract the remaining obstructing tissues. Those instruments wide enough to adequately retract larger segments of tissue cannot fit into the central groove to adequately retract this tissue. Such attempts, in fact, might actually crush or lacerate this thin piece of gingival tissue as the wider portions of tissue are retracted.
Several patents teach of instruments specifically designed for gingival tissue retraction for particular purposes. Each is designed of particular size, shape, and contour, as necessary to conform to the specific anatomy, both of the tooth and the tissue, involved, and to the particular procedure as required.
U.S. Pat. No. 4,004,345 teaches a rubber dam clamp with a separate arm designed for tissue retraction. While this arm may retract wider segments of tissue, there is no element for retracting the narrower portion of tissue lying in the central groove. In addition, even if tissue retraction were adequate, the clamp portion of this device would itself obstruct portions of the tooth that are required to be accessible for banding.
U.S. Pat. Nos. 5,358,403 and 5,899,694 teach gingival retraction by way of a loop of retraction cord that encircles the base of a tooth along the gumline or “gingival margin”. These devices are designed to work by adapting snugly to the tooth. There is no feature in these designs for retracting tissue from the narrow central groove. If this type of retractor is employed to retract larger tissues near the occlusal surface of a tooth, portions of the tissue could simply lie over the retraction cord and continue to obstruct the tooth. Even if successful in pushing the tissue away from the tooth, the retraction cord itself would surround and obstruct the circumference of the tooth.
U.S. Pat. Nos. 5,022,859 and 5,718,583 teach instruments designed to retract gingival tissues in conjunction with the placement of retraction cord. While these instruments are narrow enough to potentially retract tissue in the central groove, they have no means of retracting wider segments of tissue.
U.S. Pat. No. 4,854,867 teaches a gingival retractor specifically shaped to conform to the contours of a tooth at the base of said tooth along the gingival margin. Tooth contours near the occlusal surface are significantly different, both in dimension and geometry, than those at the gingival margin. Though this device may be successful in retracting some wider tissues near the occlusal surface, its contour would prevent its universal application. Even if numerous instruments with varying contours were obtained, there is no means for retracting tissue from the central groove. Additionally, this device is designed to keep the tissue retracted by engaging the instrument edge firmly against the tooth. Once again, such application would itself obstruct access for banding.
Accordingly, each instrument currently available and used as a gingival retraction device has a number of deficiencies for the present application. There remains in the trade a need for a single properly sized and contoured instrument designed specifically for retracting gingival tissues away from the central groove and adjacent areas of a partially obstructed posterior tooth as necessary to allow complete circumferential access for the purpose of fitting and placing orthodontic bands.